1. Field of the Invention
The invention relates generally to compositions and methods for vaginal treatments. Particularly it relates to substantially anhydrous semi-solid to solid compositions containing poloxamers. The composition forms coherent structured bi-layer gel in a moist environment at or above body temperature, which unexpectedly provides long lasting and improved moisture and lubrication.
2. Description of the Related Art
Vaginal dryness is a common condition. It may affect women of all ages. The most common cause of vaginal dryness is decreased estrogen levels, which leads to thinning and drying of the vaginal wall. However, other factors such as medical conditions and psychological conditions including stress, depression and anxiety may also contribute to vaginal dryness. Vaginal dryness may make some daily activities uncomfortable, and it can also create quality of life issues for women and their partners.
Problems due to insufficient lubrication and dryness are generally addressed by vaginal compositions that provide or restore normal lubrication and hydration functions. These compositions are in the forms of creams, gels, films, liquids, solids and foams. However, most compositions suffer from the problems such as inconvenience and can be messy to use, irritating, and poor lasting quality. As such, it is appreciated that there is an unmet need for a lubricant that is non-irritating to both partners, easy and convenient to use, and provides long lasting moisture and lubricious properties.
Various types of natural and synthetic polymers have been generally employed in the compositions for vaginal treatments utilizing the polymer's muco adhesion and prolonging effects for topical applications. Where poloxamers are included, they are commonly used in combination with bioactive compounds or optionally used with other specific polymers wherein the specific polymers provide a more specialized role such as pH maintenance. The compositions disclosed in the prior art mostly contain water as the vehicle, which require preservatives to prevent spoilage and which has the limitation that the active ingredients should be insensitive to water.
Illustratively, U.S. Pat. No. 6,913,759 discloses an aqueous composition containing benzydamine hydrochloride, polyoxyalkylene block copolymer and propylene glycol. The composition has a pH value in the range of 3.5 to 7 and is allegedly effective in treating vaginal infections.
Other vaginal treatment compositions are also known. For example, U.S. Patent No. 2006/0018951 discloses a pH-responsive film comprising a biocompatible, hydrophilic polymer such as chitosan lactate, which is positively charged at a first pH and in an electronically neutral form at a higher pH; and an alkylene oxide polymer or copolymer including poloxamers. It is disclosed that the film may be used for contraception, treatment of vaginal infections, and enhancement of vaginal lubrication.
U.S. Patent No. 2007/0104783 discloses a bioadhesive sticker tablet containing one or more bioadhesive polymers including poloxamer. Even though the patent discloses that the composition may be applied to vaginal mucosa, it is mainly used for the treatment of ulcers or lesions in the oral cavity.
WO 2004/041118 discloses polymer foams and films for delivery of therapeutic agents to and through nasal, oral or vaginal mucosa. The foams and films contain a substrate polymer and a pharmacologically effective agent. The substrate polymer may be poloxamer. The patent does not disclose a composition that is in a solid to semi solid form at ambient temperature but transforms to a gel like structure at body temperature.
As such, it is appreciated that there is still a need for another composition containing poloxamer that is effective for treating vaginal dryness and has all the desired characters of a vaginal lubricant. The present invention is believed to be an answer to that need.